Centos6 - add and remove User

Add User

sudo adduser newuser
sudo passwd newuser

Delete User

sudo userdel -r newuser

You can add the flag “-r” to the command if you would like to simultaneously remove the users’s home directory and files.

EntityManager - find list of objects

public List<Element> findAllElements(Task task) {
    logger.info("Try to find elements - task: {}", task.getId());

    return em.createNamedQuery(Element.FIND_ALL_BY_TASK, Element.class)
               .setParameter("task", task)
               .getResultList();
}

Convert public certificate to Base64

String base64Encoded = Base64.encodeToString(pubkey.getEncoded(), Base64.DEFAULT).
    replaceAll("\n", "");

Testy logów z log4j

Tworzymy klasę w /src/test/java/pakiet

import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.log4j.spi.LoggingEvent;

import java.util.ArrayList;
import java.util.List;

public class LogsHistorySaver extends AppenderSkeleton {
    private List logs;

    public void setUp() {
        logs = new ArrayList<>();
        Logger.getRootLogger().addAppender(this);
    }

    public void tearDown() {
        Logger.getRootLogger().removeAppender(this);
    }

    public List getLogs() {
        return logs;
    }

    @Override
    protected void append(LoggingEvent event) {
        logs.add(new Event(event.getLevel(), String.valueOf(event.getMessage())));
    }

    @Override
    public void close() {

    }

    @Override
    public boolean requiresLayout() {
        return false;
    }

    public class Event {
        private Level level;
        private String message;

        Event(Level level, String message) {
            this.level = level;
            this.message = message;
        }

        public Level getLevel() {
            return level;
        }

        public String getMessage() {
            return message;
        }

        @Override
        public String toString() {
            final StringBuilder sb = new StringBuilder("Event{");
            sb.append("level=").append(level);
            sb.append(", message='").append(message).append('\'');
            sb.append('}');
            return sb.toString();
        }
    }
}

I korzystamy w niej w teście w spoób następujący:

public class KaboomTest {

    private Kaboom sut;

    private LogsHistorySaver logsHistorySaver = new LogsHistorySaver();

    @Before
    public void setUp() throws Exception {
        logsHistorySaver.setUp();
    }

    @Test
    public void log() throws Exception {
        //when
        sut.build();

        //then
        List logs = logsHistorySaver.getLogs();

        assertThat(logs.size()).isEqualTo(3);
        assertThat(logs.get(0).getLevel()).isEqualTo(Level.INFO);
        assertThat(logs.get(0).getMessage()).isEqualTo("First log");
        assertThat(logs.get(1).getLevel()).isEqualTo(Level.INFO);
        assertThat(logs.get(1).getMessage()).isEqualTo("Second log");
        assertThat(logs.get(2).getLevel()).isEqualTo(Level.INFO);
        assertThat(logs.get(2).getMessage()).isEqualTo("Third log");
    }
}

Mockito - mock final class

Mockito w wersji 2.4.2 umożliwia mockowanie finalnych klas (oraz metod).

Wystarczy dodać plik

src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker

zawierający jedną linię tekstu:

mock-maker-inline

Maven dependency:

    org.mockito
    mockito-core
    2.4.2

Stream zamiast forEach

Bez użycia streama (trzeba definiować listę obiektów):

private List buildTransactions(AccountNumber accountNumber) {
    List transactions = new ArrayList<>();
    accountNumber
        .getAccountHistoryList()
        .forEach(accountHistory -> transactions.add(transactionBuilder.build(accountHistory)));

    return transactions;
}

Używając streama możemy tworzenie listy obiektów pominąć:

private List buildTransactions(AccountNumber accountNumber) {
    return accountNumber
        .getAccountHistoryList()
        .stream()
        .map(accountHistory -> transactionBuilder.build(accountHistory))
        .collect(Collectors.toList());
}

Update: Można jeszcze bardziej elegancko:

private List buildTransactions(AccountNumber accountNumber) {
    return accountNumber
        .getAccountHistoryList()
        .stream()
        .map(transactionBuilder::build)
        .collect(Collectors.toList());
}

Optional.ofNullable().orElseThrow()

Przykład wykorzystania klasy Optional dostępnej od Java 8.

Bez Optionala

public void test(Task task) throws VerificationException {
    if (task.getCustomer() == null) {
        logger.error(CUSTOMER_NOT_FOUND);
        throw BmVerificationException.badRequest(CUSTOMER_NOT_FOUND);
    }
}

Z Optionalem

public void test(Task task) throws VerificationException {
    Optional.ofNullable(task.getCustomer()).orElseThrow(this::getException);
}

private VerificationException getException() {
    logger.error(CUSTOMER_NOT_FOUND);
    return VerificationException.badRequest(CUSTOMER_NOT_FOUND);
}